diff --git a/modules/nats/cmd/nats-tools/main.go b/modules/nats/cmd/nats-tools/main.go
index ef376d51..11e00c00 100644
--- a/modules/nats/cmd/nats-tools/main.go
+++ b/modules/nats/cmd/nats-tools/main.go
@@ -157,3 +157,12 @@ func main() {
 		os.Exit(1)
 	}
 }
+
+// The seat mesh-broker's reading verbs, which this bundle serves (design 25 § 12.3): every entry, one entry, what the
+// bus holds against what was asked, and what no manifest asks for. Its acting verbs (create, apply, recreate, drop) are
+// the keeper's own work, on its own account alone (keeper.go), so no other account, the tool runner's included, holds
+// them.
+var ReadingVerbs = []string{"list", "show", "check", "orphans"}
+
+// Events are the bus module's own events (ADR 0595 §6, ADR 0620 §2), on its own stream broker-events (BROKER_EVENTS).
+var Events = []string{"created", "refused", "drifted", "drift-cleared", "full", "full-cleared", "orphaned", "recreated", "dropped"}
diff --git a/modules/nats/cmd/nats-tools/manifest_test.go b/modules/nats/cmd/nats-tools/manifest_test.go
index 93e0a8b3..e7c4c503 100644
--- a/modules/nats/cmd/nats-tools/manifest_test.go
+++ b/modules/nats/cmd/nats-tools/manifest_test.go
@@ -2,6 +2,7 @@ package main
 
 import (
 	"encoding/json"
+	"fmt"
 	"os"
 	"slices"
 	"strings"
@@ -150,6 +151,78 @@ func TestTheBussManifestMountsItsProgramsIntoTheUpstreamImage(t *testing.T) {
 			t.Errorf("the tools' credential is %q: the process nats-tools' own secret broker-nats-tools, under a word of the bundle's own (the runtime strips MESH_BROKER_FILE)", a.Env["NATS_TOOLS_CREDENTIAL"])
 		}
 	}
+	// The bus module provides bus state (design 25 § 12.2-12.3, ADR 0595 §4-§6; CAT-N1): its keeper is a process of
+	// its own on its own account (own secret broker-keeper, ADR 0436 §1), creating only bus state; it hears the indexer's
+	// manifest-accepted, keeps what it heard in its own old state `asked` (ADR 0595 §10) and the persons' requests in
+	// `requests`; its nine events are its own (ADR 0620 §2), on its own stream kept 30 days at 256 MiB; the seat's four
+	// reading verbs are served, its four acting verbs are the keeper's own work and no other account's; its health is
+	// the keeper's own tool, beside the server's tcp check.
+	var nm struct {
+		Claims []struct {
+			Name   string   `json:"name"`
+			Serves []string `json:"serves"`
+		} `json:"claims"`
+		Consumes   []string `json:"consumes"`
+		Invokes    []string `json:"invokes"`
+		Uses       []string `json:"uses"`
+		OwnSecrets map[string]json.RawMessage `json:"own-secrets"`
+		Streams    []struct {
+			Name       string   `json:"name"`
+			Events     []string `json:"events"`
+			MaxAgeDays int      `json:"max-age-days"`
+			MaxMiB     int      `json:"max-mib"`
+		} `json:"streams"`
+		State []struct {
+			Name string `json:"name"`
+		} `json:"state"`
+	}
+	if err := json.Unmarshal(raw, &nm); err != nil {
+		t.Fatal(err)
+	}
+	if len(nm.Claims) != 1 || nm.Claims[0].Name != "mesh-broker" || !slices.Equal(nm.Claims[0].Serves, ReadingVerbs) {
+		t.Errorf("claims are %+v: mesh-broker, serving its reading verbs %v alone", nm.Claims, ReadingVerbs)
+	}
+	if !slices.Equal(nm.Consumes, []string{"mesh-delivery-indexer.manifest-accepted"}) {
+		t.Errorf("consumes %v: the indexer's manifest-accepted alone (ADR 0595 §4)", nm.Consumes)
+	}
+	for _, want := range []string{"mesh-delivery-indexer.indexer_bus_state", "seat:mesh-hand-acts.hand-act"} {
+		if !slices.Contains(nm.Invokes, want) {
+			t.Errorf("invokes %v lack %s", nm.Invokes, want)
+		}
+	}
+	if !slices.Contains(nm.Uses, "operator-channel") {
+		t.Errorf("uses %v: the operator channel, for the warrant of recreate and drop", nm.Uses)
+	}
+	if len(nm.Streams) != 1 || nm.Streams[0].Name != "broker-events" || !slices.Equal(nm.Streams[0].Events, Events) ||
+		nm.Streams[0].MaxAgeDays != 30 || nm.Streams[0].MaxMiB != 256 {
+		t.Errorf("streams are %+v: broker-events carrying %v, 30 days, 256 MiB", nm.Streams, Events)
+	}
+	for _, e := range Events {
+		if slices.Contains(m.Emits, e) {
+			t.Errorf("emits lists %s, which its stream carries: an event is named in one place (ADR 0363)", e)
+		}
+	}
+	var states []string
+	for _, s := range nm.State {
+		states = append(states, s.Name)
+	}
+	if !slices.Equal(states, []string{"asked", "requests"}) {
+		t.Errorf("state is %v: asked and requests, old sections (ADR 0595 §10)", states)
+	}
+	if _, ok := nm.OwnSecrets["broker-keeper"]; !ok {
+		t.Error("own-secrets lack broker-keeper, the keeper's own account (ADR 0436 §1)")
+	}
+	keeper := byID["keeper"]
+	bus, _ := keeper["bus"].(map[string]any)
+	health, _ := keeper["health"].(map[string]any)
+	if keeper["type"] != "process" || keeper["artifact"] != "tools" || fmt.Sprint(keeper["run"]) != "[./nats-tools keep]" ||
+		fmt.Sprint(bus["state"]) != "[asked requests]" ||
+		health["kind"] != "tool" || health["tool"] != "nats_keeper_health" {
+		t.Errorf("the keeper is %v: a process of the tools bundle, run as keep, keeping asked and requests, judged by nats_keeper_health", keeper)
+	}
+	if h, _ := server["health"].(map[string]any); h["kind"] != "tcp" || h["endpoint"] != "bus" {
+		t.Errorf("the server's health is %v: tcp on bus, the check the keeper's tool check stands beside", server["health"])
+	}
 	args, _ := server["args"].([]any)
 	if len(args) != 2 || args[0] != "sh" || args[1] != "/opt/mesh-entrypoint/entrypoint.sh" {
 		t.Errorf("args are %v: the entrypoint run through sh, so no execute bit is relied on", args)
diff --git a/modules/nats/module.json b/modules/nats/module.json
index 4f028cc2..413fe33c 100644
--- a/modules/nats/module.json
+++ b/modules/nats/module.json
@@ -24,14 +24,24 @@
   "claims": [
     {
       "name": "mesh-broker",
-      "scope": "mesh"
+      "scope": "mesh",
+      "serves": [
+        "list",
+        "show",
+        "check",
+        "orphans"
+      ]
     }
   ],
   "bus-users": "/var/lib/nats-module/conf/accounts.conf",
   "core-credentials": true,
   "own-secrets": {
     "broker": "${dir:mesh-state}/broker",
-    "broker-nats-tools": "${dir:tools-secret}/broker-nats-tools"
+    "broker-nats-tools": "${dir:tools-secret}/broker-nats-tools",
+    "broker-keeper": {
+      "path": "${dir:keeper-state}/broker-keeper",
+      "owner": "nats-keeper"
+    }
   },
   "capabilities": [
     "container-runtime"
@@ -43,16 +53,51 @@
     "bucket-expiry-set"
   ],
   "invokes": [
-    "seat:mesh-hand-acts.hand-act"
+    "seat:mesh-hand-acts.hand-act",
+    "mesh-delivery-indexer.indexer_bus_state"
+  ],
+  "consumes": [
+    "mesh-delivery-indexer.manifest-accepted"
+  ],
+  "uses": [
+    "operator-channel"
+  ],
+  "streams": [
+    {
+      "name": "broker-events",
+      "events": [
+        "created",
+        "refused",
+        "drifted",
+        "drift-cleared",
+        "full",
+        "full-cleared",
+        "orphaned",
+        "recreated",
+        "dropped"
+      ],
+      "max-age-days": 30,
+      "max-mib": 256
+    }
+  ],
+  "state": [
+    {
+      "name": "asked",
+      "history": 5
+    },
+    {
+      "name": "requests",
+      "history": 5,
+      "ttl-seconds": 86400
+    }
   ],
-  "consumes": [],
   "listens": [
     {
       "name": "bus",
       "port": 4222,
       "protocol": "tcp",
       "from": "mesh",
-      "why": "the mesh bus — every link the mesh has, over TLS, reached across the overlay"
+      "why": "the mesh bus \u2014 every link the mesh has, over TLS, reached across the overlay"
     }
   ],
   "tools": [
@@ -96,6 +141,13 @@
     ]
   },
   "resources": [
+    {
+      "id": "keeper-account",
+      "type": "user",
+      "name": "nats-keeper",
+      "shell": "/usr/bin/nologin",
+      "home": "/var/lib/nats-keeper"
+    },
     {
       "id": "jetstream-data",
       "type": "directory",
@@ -117,6 +169,14 @@
       "mode": "0711",
       "unknown": "program"
     },
+    {
+      "id": "keeper-state",
+      "type": "directory",
+      "path": "/var/lib/nats-keeper",
+      "mode": "0700",
+      "owner": "nats-keeper",
+      "unknown": "program"
+    },
     {
       "id": "snapshots",
       "type": "directory",
@@ -158,6 +218,41 @@
       "artifact": "entrypoint",
       "unknown": "program"
     },
+    {
+      "id": "keeper",
+      "type": "process",
+      "name": "nats-keeper",
+      "artifact": "tools",
+      "run": [
+        "./nats-tools",
+        "keep"
+      ],
+      "user": "nats-keeper",
+      "env": {
+        "MESH_BROKER_FILE": "${dir:keeper-state}/broker-keeper",
+        "MESH_NATS_FULL_RAISE": "75",
+        "MESH_NATS_FULL_CLEAR": "70"
+      },
+      "bus": {
+        "state": [
+          "asked",
+          "requests"
+        ],
+        "asks": true,
+        "invokes": [
+          "mesh-delivery-indexer.indexer_bus_state",
+          "seat:mesh-hand-acts.hand-act"
+        ]
+      },
+      "health": {
+        "kind": "tool",
+        "tool": "nats_keeper_health",
+        "interval": "60s",
+        "timeout": "10s",
+        "looks": 2,
+        "grace": "180s"
+      }
+    },
     {
       "id": "server",
       "type": "container",
@@ -181,7 +276,11 @@
       "restart-on": [
         "program-snapshot",
         "program-entrypoint"
-      ]
+      ],
+      "health": {
+        "kind": "tcp",
+        "endpoint": "bus"
+      }
     }
   ],
   "accesses": [